The title of this project has been preserved, but the overall objectives have been modified in view of the important unresolved problems in caloric vestibular testing methodology and the strong indications from our studies that a new temperature-switching caloric irrigation method will provide a substantial improvement in the test. Thus, further study of the influence of vestibular pathways in the cerebellum upon the vestibulo-ocular reflex has been set aside in favor of our current objective, improvement in the reliability and precision of thermal vestibular tests. The magnitude of forces acting on the endolymph during thermal labyrinthine testing and hence the "stimulus intensity", is proportional to temperature changes within the lateral semicircular canal. Therefore, it is proposed to measure temperature changes within the lateral canal developing from a variety of aural irrigation methods in ex vivo human temporal bones. These experiments will be used to evaluate new methods of thermal vestibular testing, methods which already appear to be significant improvements in this clinically-important test. Recently-constructed air and water irrigation equipment will be performance-tested - and then used to apply the new caloric test to normal subjects.